HUMMM...
Hi,
Most likely it hums all the time,you may just not hear it at lower volume settings.
The taper of the old 500K may well have a different attenution curve compared to what is commonly used nowadays.
The hum may be a ground loop or some injected hum from AC fed heaters.
It is also possible that a filtercap has dried up and lets the ripple through.
Cheers,
Hi,
Most likely it hums all the time,you may just not hear it at lower volume settings.
The taper of the old 500K may well have a different attenution curve compared to what is commonly used nowadays.
The hum may be a ground loop or some injected hum from AC fed heaters.
It is also possible that a filtercap has dried up and lets the ripple through.
Cheers,
HF problems?
Just a small warning. I once had a hum develop in my power amp when the volume control went past a point. It turned out to b eHF oscillation - I could see it on the scope. WHile you cannot hear the HF ( RF) its effects filter down ! Check to see if your power transistors are heating up suddenly . The RF is usually of very low amplitude.
Just a word of caution. In your case it might be just a hum loop ----- Hmmmm.
Cheers.
Just a small warning. I once had a hum develop in my power amp when the volume control went past a point. It turned out to b eHF oscillation - I could see it on the scope. WHile you cannot hear the HF ( RF) its effects filter down ! Check to see if your power transistors are heating up suddenly . The RF is usually of very low amplitude.
Just a word of caution. In your case it might be just a hum loop ----- Hmmmm.
Cheers.
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